build: Add pkg-config file.

Makefile.am

@@ -5,6 +5,13 @@ AM_CPPFLAGS = -I$(srcdir)/include -I$(srcdir)/include/dummy
 widl_headers = \
 	include/d3d12.h
 
+vkd3d_public_headers = \
+	include/d3d12.h \
+	include/dummy/rpc.h \
+	include/dummy/rpcndr.h \
+	include/dxgibase.h \
+	include/vkd3d_windows.h
+
 BUILT_SOURCES = $(widl_headers)
 CLEANFILES = $(widl_headers)
 
@@ -12,5 +19,17 @@ lib_LTLIBRARIES = libvkd3d.la
 libvkd3d_la_SOURCES = \
 	libs/vkd3d/vkd3d_main.c
 
+pkgconfigdir = $(libdir)/pkgconfig
+pkginclude_HEADERS = $(vkd3d_public_headers)
+nodist_pkgconfig_DATA = libvkd3d.pc
+
 $(widl_headers): %.h: %.idl
 	$(WIDL) -o $@ $<
+
+libvkd3d.pc: $(srcdir)/libs/vkd3d/libvkd3d.pc.in
+	sed -e 's![@]prefix[@]!$(prefix)!g' \
+		-e 's![@]exec_prefix[@]!$(exec_prefix)!g' \
+		-e 's![@]includedir[@]!$(includedir)!g' \
+		-e 's![@]libdir[@]!$(libdir)!g' \
+		-e 's![@]PACKAGE_VERSION[@]!$(PACKAGE_VERSION)!g' \
+		$< > $@